It comes after a succession of deaths in recent days after people got into trouble in open water after seeking refuge from the heatwave.

The bodies of two swimmers were found in a popular beauty spot in lakes at Bawsey Pits, a disused quarry in west Norfolk, last night.

A 16-year-old originally from London living in Ely, Cambridgeshire, and a 41-year-old man from King’s Lynn, Norfolk, were both found entangled in reeds about two metres below the surface.

Bawsey Pits on the outskirts of King's Lynn (Google)

It is believed the 41-year-old had swum about 50 metres out in one of the flooded quarries towards an island before he was seen disappearing below the water. The teenager was reported missing at another lake about half a mile away.

Police have told people to stay away from the quarry, which is popular with sunseekers, but many ignore the warning signs.

The deaths of the two males are just the latest in a series of tragic incidents.

A 21-year-old from Shropshire also died yesterday evening after struggling in the river Dee on the England-Wales border.

After a search aided by a police helicopter, he was discovered around 8pm where the rivers Dee and Ceiriog merge near Chirk, North Wales. He was airlifted to the Royal Shrewsbury Hospital where he later died.

A West Mercia police warned swimmers not to be "tempted" to cool off in open water after a number of similar deaths.

A force spokesman said: "There have been a number of recent tragedies in Shropshire and neighbouring counties where people have got into difficulties after entering rivers or quarry pools.

"Please don't be tempted. These types of water can be highly dangerous with strong under currents, low temperatures which can cause muscle cramps and hidden obstacles beneath the surface. Sadly, we are now dealing with another such tragedy."

Kent Police have also warned people not to go into the River Thames after a rescuer was feared drowned at Gravesend.

Nathan Lane, 28, has not been seen since getting into difficulties at Newbridge Causeway trying to rescue a girl.

Mr Lane was swept away despite of the efforts of four nearby schoolchildren who did their best to save him.

Two Territorial Army soldiers died last weekend during a selection for the SAS reserves, as they collapsed in temperatures approaching 30C on the Brecon Beacons.

Lance Corporal Craig Roberts collapsed and died along with another soldier as they took part in a gruelling time trial in the Welsh mountains on what was the hottest day of the year so far.

A British woman who was swimming across the English Channel for charity suffered a cardiac arrest as she was a mile from the French Coast.

More than £70,000 has been raised in the memory of Susan Taylor, a 34-year-old accountant from Barwell, Leicestershire.

Justas Juzenas, 22, also drowned at Gullet Quarry, a stretch of water near Malvern, Worcestershire, where 17-year-old Russell O'Neill died on July 6.

Last Wednesday the body of Hollie McClymont, 14, was recovered from the sea near Barry Island in Wales.

The teenager, who was on a family holiday, had been seen three days earlier getting into difficulty while swimming off Whitmore Bay.